Diagnosis of suspected venous thromboembolic disease in pregnancy

Computed tomography diagnosed left ovarian venous thrombophlebitis after vaginal delivery: A case report

BACKGROUND

Postpartum ovarian vein thrombophlebitis (POVT) is a rare but serious postpartum complication that affects mostly postpartum women. A high index of suspicion is required when faced with sudden postpartum abdominal pain.

CASE SUMMARY

A 25-year-old healthy woman who accepted a vaginal delivery procedure suffered fever (temperature 39.6℃) one day after delivery, accompanied with left lower abdominal pain. Physical examination indicated mild tenderness in the left lower abdomen, accompanied with rebound pain. The patient was confirmed to have left ovarian venous thrombosis with inflammation after receiving a multi-detector row computed tomography scan.

CONCLUSION

POVT is a rare and dangerous postpartum complication. A high index of suspicion is required for the occurrence of ovarian venous thrombosis when faced with postpartum abdominal pain and fever. Early application of Doppler ultrasound, computed tomography, magnetic resonance imaging and other auxiliary examinations is conducive to timely and accurate diagnosis of POVT, thus reducing maternal mortality.

Clinical Characteristics and Management of Ovarian Vein Thrombosis: A Case Series

Background

Ovarian vein thrombosis (OVT) is an uncommon condition, occurring in ~1 in every 600–2,000 pregnancies. It is associated with various conditions, including thrombophilia, malignancy, sepsis, intra-abdominal and pelvic inflammatory conditions, pregnancy, and the postpartum period, and specific surgical interventions, particularly gynecological surgeries. Thus, this study aims to identify the associated factors for OVT and elaborate on the standard treatment strategies for its management.

Methods

Retrospective data collection was used. Our study consists of 18 patients diagnosed with OVT between 2005 and 2016; the data was collected from the Health Information Management system at King Fahad Medical City, Riyadh, Saudi Arabia using a standard format.

Results

Our study found that OVT involves the right ovarian vein more often than the left and mainly occurs in women during their postpartum period. These patients other associated factor included hypertension, diabetes, and a higher body mass index (BMI) of above 25 kg/m². The most frequently presenting complaints were abdominal pain and fever. The most common treatment was the administration of enoxaparin (a low molecular weight heparin) for an average duration of one to three months, which resulted in a low recurrence rate of OVT.

Conclusions

Physicians should be vigilant for suspicion of OVT in female patients presenting with lower abdominal pain and fever in their postpartum period. Additionally, it is suggested to use low molecular weight heparin as initial therapy for OVT for one to three months, resulting in a high remission rate.

Imaging during pregnancy: What the radiologist needs to know

During the last decades, there has been a growing demand for medical imaging in gravid women. Imaging of the pregnant woman is challenging as it involves both the mother and the fetus and, consequently, several medical, ethical, or legal considerations are likely to be raised. Theoretically, all currently available imaging modalities may be used for the evaluation of the pregnant woman; however, in practice, confusion regarding the safety of the fetus often results in unnecessary avoidance of useful diagnostic tests, especially those involving ionizing radiation. This review article is focused on the current safety guidelines and considerations regarding the use of different imaging modalities in the pregnant population; also presented is an imaging work-up for the most common medical conditions of pregnant women, with emphasis on fetal and maternal safety.

Advances in the Diagnosis of Venous Thromboembolism: A Literature Review

The incidence of venous thromboembolism (VTE), including lower extremity deep vein thrombosis (DVT) and pulmonary embolism (PE) is increasing. The increase in suspicion for VTE has lowered the threshold for performing imaging studies to confirm diagnosis of VTE. However, only 20% of suspected cases have a confirmed diagnosis of VTE. Development of pulmonary embolism rule-out criteria (PERC) and update in pre-test probability have changed the paradigm of ruling-out patient with low index of suspicion. The D-dimer test in conjunction to the pre-test probability has been utilized in VTE diagnosis. The age appropriate D-dimer cutoff and inclusion of YEARS algorithm (signs of the DVT, hemoptysis and whether PE is the likely diagnosis) for the D-dimer cutoff have been recent updates in the evaluation of suspected PE. Multi-detector computed tomography pulmonary angiography (CTPA) and compression ultrasound (CUS) are the preferred imaging modality to diagnose PE and DVT respectively. The VTE diagnostic algorithm do differ in pregnant individuals. The prerequisite of avoiding excessive radiation has recruited planar ventilation-perfusion (V/Q) scan as preferred in pregnant patients to evaluate for PE. The modification of CUS protocol with addition of the Valsalva maneuver should be performed while evaluating DVT in pregnant individual.

Evaluation of CTPA interpreted as limited in pregnant patients suspected for pulmonary embolism

PURPOSE

The purpose of this study is to determine the rates of CT pulmonary angiography (CTPA) interpreted as limited and severely limited in pregnant patients suspected for pulmonary embolism (PE), and to evaluate factors that influence these rates.

METHODS

This is a retrospective study with CTPA for evaluation of PE in pregnancy across a large health system from 2006 to 2017. CTPA was classified as limited from the radiology report with a subset of those studies classified as severely limited. Bivariate and multivariate analysis was performed for limited and severely limited rates with maternal age and patient size as a continuous variable and race, trimester, patient location study priority status, and result of chest radiograph before CTPA as categorical variables.

RESULTS

874 patients with 33% of studies limited and 4% of studies severely limited. Multivariate logistic regression of CTPA studies revealed decreasing patient age (OR 0.967, p = 0.0129) and increasing patient size (OR 1.013, p < 0.0001). Studies performed in the second trimester (OR 1.869, p = 0.0242) and third trimester (OR 2.314, p = 0.0021) were more likely to be reported as limited (each p < 0.05). Increasing patient size (OR 1.017, p = 0.0046) was the only significant predictor of severely limited versus non-severely limited studies.

CONCLUSION

CTPA interpreted as limited in pregnancy are common and may be associated with younger age, larger patient size, and second and third trimesters. However, severely limited interpretations are much less common, with patient size the only significant predictor.

American Society of Hematology 2018 guidelines for management of venous thromboembolism: venous thromboembolism in the context of pregnancy

BACKGROUND

Venous thromboembolism (VTE) complicates ∼1.2 of every 1000 deliveries. Despite these low absolute risks, pregnancy-associated VTE is a leading cause of maternal morbidity and mortality.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians and others in decisions about the prevention and management of pregnancy-associated VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations.

RESULTS

The panel agreed on 31 recommendations related to the treatment of VTE and superficial vein thrombosis, diagnosis of VTE, and thrombosis prophylaxis.

CONCLUSIONS

There was a strong recommendation for low-molecular-weight heparin (LWMH) over unfractionated heparin for acute VTE. Most recommendations were conditional, including those for either twice-per-day or once-per-day LMWH dosing for the treatment of acute VTE and initial outpatient therapy over hospital admission with low-risk acute VTE, as well as against routine anti-factor Xa (FXa) monitoring to guide dosing with LMWH for VTE treatment. There was a strong recommendation (low certainty in evidence) for antepartum anticoagulant prophylaxis with a history of unprovoked or hormonally associated VTE and a conditional recommendation against antepartum anticoagulant prophylaxis with prior VTE associated with a resolved nonhormonal provoking risk factor.

Overuse and underuse of pulmonary CT angiography in patients with suspected pulmonary embolism

Background: The aim of the present study was to evaluate the utilization and diagnostic yields of CT pulmonary angiography (CTPA)using the Revised Geneva score and Wells’ criteria, in patients with suspected pulmonary embolism (PE).

Methods: One hundred and twelve adult patients underwent CTPA for suspected PE were participated in this study. The outcome was positive or negative CTPA for PE. Revised Geneva and Wells’ scores were calculated. The relationship between the results obtained rom these two scores and the available risk factors were compared. Descriptive analysis such as frequency and mean as well as analytical statistics including chi-square were done. The data analysis was performed using SPSS (v. 22).

Results: In this study, according to the Wells’ criteria calculated for the patients, 33.9% of the patients had low clinical, 56.3% intermediate and 9.8% high clinical probability. Among the 11 high clinical patients, 9(81.8%) were CTPA positive. Based on the revised Geneva score, 65 patients (58%) had low clinical, 36 (32.1%) intermediate and 11(9.8%) high clinical probability. Among the 1 high clinical patients, 8 were CTPA positive. Positive predictive value of the low clinical patients based on Wells’ criteria and the revised Geneva score was 18.4% and 30.8%, respectively. Also, positive predictive value for high clinical probability of Wells’ criteria and the revised Geneva score was 81.8% and 72.8% respectively.

Conclusion: Under/overuse of CTPA in diagnosing PTE is a common problem especially in university hospitals. It is possible to avoid unnecessary CTPA requests using scholarly investigations and more accurate clinical risk assessments.

"Pulmonary embolism diagnostics of pregnant patients: What is the recommended clinical pathway considering the clinical value and associated radiation risks of available imaging tests?"

Pulmonary embolism (PE) during pregnancy remains the leading preventable cause of maternal morbidity and mortality in the developed countries. Diagnosis of PE in pregnant patients is a challenging clinical problem, since pregnancy-related physiologic changes can mimic signs and symptoms of PE. Patient mismanagement may result into unjustified anticoagulant treatment or unnecessary imaging tests involving contrast-related or/and radiation-related risks for both the expectant mother and embryo/fetus. On the other hand, missing or delaying diagnosis of PE could lead to life-threatening conditions for both the mother and the embryo/fetus. Thus, a timely and accurate diagnostic approach is required for the optimal management of pregnant patients with suspected PE. Aim of the current review is to discuss a pregnancy-specific clinical pathway for the early diagnosis of PE with non-ionizing radiation- and ionizing radiation-based imaging modalities taking into account previously reported data on diagnostic value of available imaging tests, and radiation related concerns.

Pulmonary thrombo-embolism in pregnancy: diagnosis and management

KEY POINTS

Venous thromboembolism (VTE) in pregnancy remains a leading cause of direct maternal mortality in the developed world and identifiable risk factors are increasing in incidence.VTE is approximately 10-times more common in the pregnant population (compared with non-pregnant women) with an incidence of 1 in 1000 and the highest risk in the postnatal period.If pulmonary imaging is required, ventilation perfusion scanning is usually the preferred initial test to detect pulmonary embolism within pregnancy. Treatment should be commenced on clinical suspicion and not be withheld until an objective diagnosis is obtained.The mainstay of treatment for pulmonary thromboembolism in pregnancy is anticoagulation with low molecular weight heparin for a minimum of 3 months in total duration and until at least 6 weeks postnatal. Low molecular weight heparin is safe, effective and has a low associated bleeding risk.

EDUCATIONAL AIMS

To inform readers about the current guidance for diagnosis and management of pulmonary thromboembolism in pregnancy.To highlight the risks of venous thromboembolism during pregnancy.To introduce the issues surrounding management of pulmonary thromboembolism around labour and delivery.

Risks to the fetus from diagnostic imaging during pregnancy: review and proposal of a clinical protocol

Every day, medical practitioners face the dilemma of exposing pregnant or possibly pregnant patients to radiation from diagnostic examinations. Both doctors and patients often have questions about the risks of radiation. The most vulnerable period is between the 8th and 15th weeks of gestation. Deterministic effects like pregnancy loss, congenital malformations, growth retardation and neurobehavioral abnormalities have threshold doses above 100-200 mGy. The risk is considered negligible at 50 mGy and in reality no diagnostic examination exceeds this limit. The risk of carcinogenesis is slightly higher than in the general population. Intravenous iodinated contrast is discouraged, except in highly selected patients. Considering all the possible noxious effects of radiation exposure, measures to diminish radiation are essential and affect the fetal outcome. Nonionizing procedures should be considered whenever possible and every radiology center should have its own data analysis on fetal radiation exposure. In this review, we analyze existing literature on fetal risks due to radiation exposure, producing a clinical protocol to guide safe radiation use in a clinical setting.

Ten years of imaging for pulmonary embolism: too many scans or the tip of an iceberg?

AIM

To examine the number and nature of investigations performed for suspected pulmonary embolism (PE) in a large teaching hospital and the change in incidence and severity of PE over a decade.

MATERIALS AND METHODS

In this retrospective study, all patients investigated for suspected PE using computed tomography pulmonary angiography (CTPA) or lung scintigraphy during 10 years to March 2012 were identified and their records reviewed. In the final year, all reportedly positive CTPA cases were reviewed and PE severity calculated, for comparison with similar historical data.

RESULTS

From 2002 to 2012, total annual investigations for suspected acute PE increased by 163% (805 to 2121). CTPA increased by 325% (475 to 2019). Detection of PE increased by 121% (193 to 426 per annum), with stable distribution of severity scores. The positive scan rate decreased from 24% to 20%. The mean age of patients being investigated for PE increased from 56 to 63 years.

CONCLUSIONS

Increased detection of PE is not due to disproportionate increase in small PEs, but to increased detection of PE of all severities. This finding supports the hypothesis that PE is more common in the general population than previously appreciated, which may represent an iceberg phenomenon of previously undetected disease.

Ovarian vein thrombosis

Ovarian vein thrombosis (OVT) is a rare cause of abdominal pain that may mimic a surgical abdomen. It is most often diagnosed during the postpartum period. In this report, we present four cases of postoperative ovarian vein thrombosis. The complications of OVT can be significant, and the diagnosis relies on a careful examination of the radiographic findings. It can occur with lower quadrant abdominal pain, especially in the setting of recent pregnancy, abdominal surgery, pelvic inflammatory disease, or malignancy. Diagnosis can be made with confidence using ultrasound, computed tomography or magnetic resonance imaging. Treatment of ovarian vein thrombosis is particularly important in the post-partum patients, with anticoagulation therapy being the current recommendation.

Imaging diagnosis of acute pulmonary embolism

Pulmonary embolism represents a major public healthcare problem and it also imposes frequent clinical diagnostic issues. Despite the availability of the D-dimer tests, imaging remains the mainstay for its diagnosis. Computed tomography pulmonary angiography (CTPA) is now the most widely used diagnostic test and its utility has been well validated in a large number of trials. Nuclear medicine techniques, which are also well established, are now used significantly less frequently. Magnetic resonance pulmonary angiography is developing as an alternative to CTPA in patients who have contraindications to iodinated contrast media. Catheter pulmonary angiography remains the gold standard, although it is being used increasingly less frequently. In this article, we review the current knowledge on the imaging diagnosis of acute pulmonary embolism with special emphasis on the noninvasive techniques.

Thoracic magnetic resonance imaging: pulmonary thromboembolism

Ongoing technical developments have substantially improved the potential of magnetic resonance imaging (MRI) in the assessment of the pulmonary circulation. These developments includes improved magnet and hardware design, new k-space sampling techniques (ie, parallel imaging), and alternative contrast materials. With these techniques, not only can pulmonary vessels be visualized by MR angiography with high spatial resolution but also the perfusion of the lungs and its changes in relation to pulmonary thromboembolism (PE) can be assessed. Considering venous thromboembolism as a systemic disease, MR venography might be added for the diagnosis of underlying deep venous thrombosis. A unique advantage of MRI over other imaging tests is its potential to evaluate changes in cardiac function as a result of obstruction of the pulmonary circulation, which may have a significant impact on patient monitoring and treatment. Finally, MRI does not involve radiation, which is advantageous, especially in young patients. Over the years, a number of studies have shown promising results not only for MR angiography but also for MRI of lung perfusion and for MR venography. This review article summarizes and discusses the current evidence on pulmonary MRI for patients with suspected PE.

Pulmonary embolism

Pulmonary embolism (PE) remains one of the most challenging medical diseases in the emergency department. PE is a potentially life threatening diagnosis that is seen in patients with chest pain and/or dyspnea but can span the clinical spectrum of medical presentations. In addition, it does not have any particular clinical feature, laboratory test, or diagnostic modality that can independently and confidently exclude its possibility. This article offers a review of PE in the emergency department. It emphasizes the appropriate determination of pretest probability, the approach to diagnosis and management, and special considerations related to pregnancy and radiation exposure.

Diagnosis of DVT: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Objective testing for DVT is crucial because clinical assessment alone is unreliable and the consequences of misdiagnosis are serious. This guideline focuses on the identification of optimal strategies for the diagnosis of DVT in ambulatory adults.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that clinical assessment of pretest probability of DVT, rather than performing the same tests in all patients, should guide the diagnostic process for a first lower extremity DVT (Grade 2B). In patients with a low pretest probability of first lower extremity DVT, we recommend initial testing with D-dimer or ultrasound (US) of the proximal veins over no diagnostic testing (Grade 1B), venography (Grade 1B), or whole-leg US (Grade 2B). In patients with moderate pretest probability, we recommend initial testing with a highly sensitive D-dimer, proximal compression US, or whole-leg US rather than no testing (Grade 1B) or venography (Grade 1B). In patients with a high pretest probability, we recommend proximal compression or whole-leg US over no testing (Grade 1B) or venography (Grade 1B).

CONCLUSIONS

Favored strategies for diagnosis of first DVT combine use of pretest probability assessment, D-dimer, and US. There is lower-quality evidence available to guide diagnosis of recurrent DVT, upper extremity DVT, and DVT during pregnancy.

Pregnancy-associated venous thrombosis

Pregnant women are at an increased risk of venous thromboembolism (VTE) and the consequences of an acute event in pregnancy can be debilitating, long-lasting or fatal. Screening for risk factors early in pregnancy and the provision of thromboprophylaxis are useful ways of preventing VTE in some women, but even when performed diligently, acute events are likely to remain common for the foreseeable future. It is therefore important for obstetric and non-obstetric clinicians to recognize the symptoms and signs of deep vein thrombosis and pulmonary embolism in pregnancy, to understand how a diagnosis can be reached in an effective yet safe manner and to be aware of the available treatment modalities.

Multimodality imaging of the peripheral venous system

The purpose of this article is to review the spectrum of image-based diagnostic tools used in the investigation of suspected deep vein thrombosis (DVT). Summary of the experience gained by the author as well as relevant publications, regarding vein imaging modalities taken from a computerized database, was reviewed. The imaging modalities reviewed include phlebography, color Doppler duplex ultrasonography (CDDUS), computerized tomography angiography (CTA) and venography (CTV), magnetic resonance venography (MRV), and radionuclide venography (RNV). CDDUS is recommended as the modality of choice for the diagnosis of DVT. A strategy combining clinical score and D-dimer test refines the selection of patients. Phlebography is reserved for discrepant noninvasive studies.

Peripartum pulmonary embolism

Pregnancy is an example of Virchow's triad predisposing to the development of venous thromboembolism (VTE). Specific risk factors for antepartum and postpartum VTE have been identified. The diagnosis of pulmonary embolism in pregnancy is complicated by the physiologic changes of pregnancy as well as physicians' apprehension about ordering radiologic studies during pregnancy because of concerns with fetal well-being. Therapy for VTE is complicated by pregnancy physiology affecting medication pharmacokinetics and bioavailability, and the unpredictable occurrence of labor during therapeutic anticoagulation.

Controversies in Diagnosis of Pulmonary Embolism

The approach to the diagnosis of acute pulmonary embolism (PE) is under constant revision with advances in technology, noninvasive approaches, and increasing awareness of the risks of ionizing radiation. Optimal approaches in some categories of patients are controversial. Data are insufficient for evidence-based recommendations. Therefore, this survey of investigators in the field was undertaken. Even among experts there were marked differences of opinion regarding the approach to the diagnosis of acute PE. Although CT pulmonary angiography was usually the imaging test of choice, the respondents were keenly aware of the dangers of ionizing radiation. In view of advances in scintigraphic diagnosis since the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) trial, ventilation/perfusion (V/Q) lung scans or perfusion scans alone and single photon emission computed tomography (SPECT) V/Q lung scans are often recommended. The choice depends on the patient’s age, gender, and complexity of the findings on the plain chest radiograph.

Dose reduction in computed tomographic angiography of pregnant patients with suspected acute pulmonary embolism

PURPOSE

The aim of this study was to quantify the effect of a reduced-dose pulmonary computed tomographic (CT) angiography protocol on radiation dose and image quality in pregnant patients as compared with a standard protocol.

MATERIALS AND METHODS

Twenty-six pregnant women with suspected pulmonary embolism underwent reduced-dose CT angiography (200 mA and 100 kV, from the aortic arch to the diaphragm). The matched control group standard protocol was 400 mA, 120 kilovolt (peak), and the entire thorax. The CT dose index, dose-length product, effective dose, image quality, and signal-to-noise ratio were assessed and compared with the Wilcoxon rank sum test result.

RESULTS

The CT dose index, mean dose-length product, and calculated effective dose were lower in the pregnancy group than in the controls: mean (SD), 5.21 (1.54) mGy versus 20.86 (5.59) mGy; 105.65 (39.77) mGy cm versus 575.71 (154.86) mGy cm, and 1.79 (0.676) msv versus 9.787 (2.63) msv, respectively (P < 0.0001). Quality scores of segmental (P = 0.266) and subsegmental (P = 0.207) arteries and arterial attenuation (P = 0.443) were similar.

CONCLUSIONS

In pregnant patients with suspected pulmonary embolism, combined reduction of kilovoltage and milliampere-second settings and z-axis coverage results in a substantial reduction of radiation dose while maintaining diagnostic imaging quality.

Pulmonary embolism: optimizing the diagnostic imaging approach

Venous thromboembolism is a common medical problem that can affect a wide range of patients. The clinical presentation ranges from minor, nonspecific signs and symptoms to severe clinical scenarios. The combination of objective pretest clinical probability, D-dimer testing, and imaging studies plays a critical role in its diagnosis. There are multiple imaging modalities to confirm or exclude the presence of pulmonary embolism and deep vein thrombosis, but, at present, computed tomography angiography is the most frequently used. Other imaging, however, is required for several subpopulations.

Pulmonary embolism in pregnancy: comparison of pulmonary CT angiography and lung scintigraphy

OBJECTIVE

The purpose of this study was to retrospectively compare the diagnostic adequacy of lung scintigraphy with that of pulmonary CT angiography (CTA) in the care of pregnant patients with suspected pulmonary embolism.

MATERIALS AND METHODS

Patient characteristics, radiology report content, additional imaging performed, final diagnosis, and diagnostic adequacy were recorded for pregnant patients consecutively referred for lung scintigraphy or pulmonary CTA according to physician preference. Measurements of pulmonary arterial enhancement were performed on all pulmonary CTA images of pregnant patients. Lung scintigraphy and pulmonary CTA studies deemed inadequate for diagnosis at the time of image acquisition were further assessed, and the cause of diagnostic inadequacy was determined. The relative contribution of the inferior vena cava to the right side of the heart was measured on nondiagnostic CTA images and compared with that on CTA images of age-matched nonpregnant women, who were the controls.

RESULTS

Twenty-eight pulmonary CTA examinations were performed on 25 pregnant patients, and 25 lung scintigraphic studies were performed on 25 pregnant patients. Lung scintigraphy was more frequently adequate for diagnosis than was pulmonary CTA (4% vs 35.7%) (p = 0.0058). Pulmonary CTA had a higher diagnostic inadequacy rate among pregnant than nonpregnant women (35.7% vs 2.1%) (p < 0.001). Transient interruption of contrast material by unopacified blood from the inferior vena cava was identified in eight of 10 nondiagnostic pulmonary CTA studies.

CONCLUSION

We found that lung scintigraphy was more reliable than pulmonary CTA in pregnant patients. Transient interruption of contrast material by unopacified blood from the inferior vena cava is a common finding at pulmonary CTA of pregnant patients.

Prevention and treatment of venous thromboembolism during pregnancy

Women who are pregnant or have recently given birth are at significantly increased risk of venous thromboembolism (VTE) compared with the general population. Furthermore, the issues surrounding the appropriate prevention, diagnosis, and treatment of VTE are more complex in pregnancy, where not only the effects on the mother, but also the effects on the fetus need to be considered. Although guidelines provide recommendations for the optimal management of these patients, most of these guidelines are based on evidence from observational studies, or on data extrapolated from a nonpregnant population. Randomized clinical trials are needed to identify the optimal strategies for prevention and treatment of VTE in pregnancy.

Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations

Use of diagnostic imaging studies for evaluation of pregnant patients with medical conditions not related to pregnancy poses a persistent and recurring dilemma. Although a theoretical risk of carcinogenesis exists, there are no known risks for development of congenital malformations or mental retardation in a fetus exposed to ionizing radiation at the levels typically used for diagnostic imaging. An understanding of the effects of ionizing radiation on the fetus at different gestational stages and the estimated exposure dose received by the fetus from various imaging modalities facilitates appropriate choices for diagnostic imaging of pregnant patients with nonobstetric conditions. Other aspects of imaging besides radiation (ie, contrast agents) also carry potential for fetal injury and must be taken into consideration. Imaging algorithms based on a review of the current literature have been developed for specific nonobstetric conditions: pulmonary embolism, acute appendicitis, urolithiasis, biliary disease, and trauma. Imaging modalities that do not use ionizing radiation (ie, ultrasonography and magnetic resonance imaging) are preferred for pregnant patients. If ionizing radiation is used, one must adhere to the principle of using a dose that is as low as reasonably achievable after a discussion of risks versus benefits with the patient.

MDCT of acute thrombotic and nonthrombotic pulmonary emboli

Acute pulmonary embolism (PE) remains a common clinical challenge. MDCT pulmonary angiography has become the first line imaging study in the diagnosis of PE because of its speed, accuracy, low-interobserver variability, and ability to provide alternative diagnoses. This review article highlights the role of MDCT in the evaluation of acute thrombotic PE in the era of PIOPED 2. MDCT findings of acute PE and some potential pitfalls are covered as well as some of the controversies in imaging young and pregnant patients. MDCT findings of acute non-thrombotic PE are also covered. This latter group may be occult on the angiographic portion of the study but may declare themselves through secondary findings. Their findings and potential mimics are included so that the interpreting radiologist can make the most of a CT to rule out PE.

[Pregnancy and lungs]

Respiratory pathology can be relatively frequent during pregnancy. One third of pregnant woman may experience worsening of their asthma condition. Pulmonary tromboembolism is 5 times more frequent in pregnancy. Bacterial, viral and fungal pneumonias are badly tolerated during pregnancy, provoking mother-foetal morbidity, respiratory insufficiency, low born-weight or prematurity. Non-treated tuberculosis may increase maternal mortality and preterm birth by 4 and 9 times respectively. Pregnancy is counter-indicated in women with cystic fibrosis and severe pulmonary function. Despite therapeutic progresses already made, pulmonary hypertension is associated to over 30% of mother-foetal morbidity and mortality. Approximately 1 in 1,000-1,500 pregnancies is affected by mother cancer. High rates of lung cancer morbility in women bring new and important challenges to therapy.

MRT der akuten Lungenembolie

Recent technical developments have substantially improved the potential of MRI for the diagnosis of pulmonary embolism. On the MR scanner side this includes the development of short magnets and dedicated whole-body MRI systems, which allow a comprehensive evaluation of pulmonary embolism and deep venous thrombosis in a single exam. The introduction of parallel imaging has substantially improved the spatial and temporal resolution of pulmonary MR angiography. By combining time-resolved pulmonary perfusion MRI with high-resolution pulmonary MRA a sensitivity and specificity of over 90% is achievable, which is comparable to the accuracy of CTA. Thus, for certain patient groups, such as patients with contraindications to iodinated contrast media and young women with a low clinical probability for pulmonary embolism, MRI can be considered as a first-line imaging tool for the assessment of pulmonary embolism.